Calcium blood test

Definition

The calcium blood test measures the level of calcium in the blood.

This article discusses the test to measure the total amount of calcium in your blood. About half of the calcium in the blood is attached to proteins, mainly albumin. For this reason, the calcium blood test can be misleading, and sometimes needs tests to confirm the result.

A separate test measures calcium that is not attached to proteins in your blood. Such calcium is called free or ionized calcium.

Alternative Names

How the Test is Performed

How to Prepare for the Test

The health care provider may tell you to temporarily stop taking certain medicines that can affect the test. Medicines include:

Calcium salts (may be found in nutritional supplements or antacids)

Lithium

Thiazide diuretics

Thyroxine

Vitamin D

Drinking too much milk (two or more quarts a day or having an equivalent amount of other dairy products ) or taking too much vitamin D as a dietary supplement can also increase blood calcium levels.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or slight bruising. These soon go away.

Why the Test is Performed

All cells need calcium in order to work. Calcium helps build strong bones and teeth. It is important for heart function, and helps with muscle contraction, nerve signaling, and blood clotting.

Your doctor may order this test if you have signs or symptoms of:

Certain bone diseases

Certain cancers, such as multiple myeloma, a cancer of the breast, lung, neck, and kidney

Your doctor may also order this test if you have been on bed rest for a long time.

Normal Risks

Normal values range from 8.5 to 10.2 mg/dL.

Normal value ranges may vary slightly among different laboratories. Some laboratories use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

Higher than normal levels may be due to a number of health conditions. Common causes include:

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

Version Info

Last reviewed on 10/29/2013

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.

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